1. Field of the Invention
The present invention relates to an electronic circuit device having a thin film resistor and a method for producing the same, and more particularly to an electronic circuit device for use in a multilayer wiring board, a heater element and the like and a method for producing the same.
2. Description of the Background Art
In a conventional electronic circuit device, a thin film resistor is formed on an insulating substrate made of a ceramic or the like or on an insulating film or the like laminated on the substrate by using a thin film technique such as sputtering or the like.
The thin film resistor of this kind, for example, is used for a resistor device in an electronic circuit, a resistor device in a thin film multilayer wiring board, or a heater device of a thermal print head in a printer or facsimile. In such a use, for example, a thin film multilayer wiring board, the following conditions are required, that is, a resistance can be determined to a predetermined value, a resistance value change with the passage of time is small, and a resistance value change with a temperature variation is small. Further, it is also desired that, even when a high temperature is repeatedly added to, its characteristics are not changed.
Conventionally, a thin film resistor is composed of a Cr-Si alloy, a Cr-SiO compound, a Cr-Si-SiO compound or the like, as disclosed in U.S. Pat. No. 4,343,986 and Japanese Patent Laid-Open Specifications Nos. 54-1898 and 58-84401.
However, when a conventional thin film resistor, for instance, is held in an atmosphere of a temperature of approximately 200.degree. to 300.degree. C. for a long time, the resistance value is changed as the time passes, and an operation of an electronic circuit becomes unstable, resulting in that the expected efficiency can not be maintained.
For example, in a thin film wiring board, an insulating layer of a resin material such as a polyimide or the like is interposed between conductive layers to laminate a plurality of wiring layers. In this process, in order to cure the polyimide, the board is heated to several hundreds .degree.C. of temperature and the heating is held a certain time of period. Accordingly, when a thin film resistor is provided in any layer of the multilayer wiring board, the resistance value of the thin film resistor is irreversibly changed by the curing. Further, since the resistance value change is not regular, even when the resistance value of the thin film resistor is designed in consideration of the resistance value change at its film formation, the resistance value is often changed to a value outside of its desired value or range, and thus a yield and productivity of the thin film resistor is low.
When a thin film resistor is used for a heater device, by repeating a heat generation, its resistance value is largely changed, and the desired heat generating capacity is not obtained. In an extreme case, a wiring is cut down or the resistor is broken. In a thermosensible recording head, when such a reduction of the heat generation capacity is caused, a printing is not effected at a heater device present portion to bring about a blank portion.